1. Field of the Invention
The present invention relates to a multistage gas and liquid phase separation condenser for condensing and separating initially introduced gaseous refrigerant of high pressure into gas and liquid. In particular, after refrigerant is separated into gas and liquid, the multistage gas and liquid phase separation condenser of the invention can improve the sub-cooling rate of liquid refrigerant while it flows through a pre-sub-cooling section and additionally in other sections.
2. Background of the Related Art
A condenser liquefies refrigerant of high temperature and pressure fed from a compressor via heat exchange between refrigerant and ambient air. A receiver tank or section is arranged between the condenser and an expansion valve and temporarily stores liquefied refrigerant from the condenser so that liquid refrigerant can be fed into an evaporator according to a desired amount of cooling load.
Recently, condensers each having a receiver tank integrally attached thereto are widely commercialized in order to maximize space utilization in an engine room of a vehicle.
Of the condensers each having an integral receiver tank, it is developed a multistage gas and liquid phase separation condenser which comprises a pair of headers and a receiver tank provided in one of the headers.
U.S. Pat. No. 5,203,407 discloses a conventional multistage gas and liquid phase separation condenser or heat exchanger.
As shown in FIG. 6, the conventional heat exchanger 1 comprises a plurality of flat tubes 2 and corrugated fins 3, which are mounted on a pair of header tanks 4 opposed to each other.
Each header 4 comprises blind caps 5 at opposite ends, three baffles or partitions 6 and 6xe2x80x2 and four compartments 8a. 
The header tank 4 on the inlet side is provided with a tank member or separate member 7 which defines on the outer side of this header tank 4, an inlet pipe 9 is connected to the tank member 7, and a distributing chamber 8 is in communication with the a pair of refrigerant passages 2A and 2B through respective communication ports 10a, 10b provided in the header tank 4.
The header 4 has a separate member 11 formed outside, and a refrigerant collecting chamber 12 is connected with a pair of refrigerant passages 2A and 2B via ports 13a and 13b in the header 4.
In this heat exchanger 1, after introduced into the distributing chamber 8 via the inlet pipe 8, refrigerant partially flows into the upper refrigerant passage 2A via the communication port 10a and partially feeds into the lower refrigerant passage 2B via the communication port 10b. 
Then, a partial refrigerant flow through the upper refrigerant passage 2A is introduced into the collecting chamber 12 via the port 13a, and another partial refrigerant flow through the lower refrigerant passage 2B is introduced via the port 13b into the collecting chamber 12, where refrigerant exits via an outlet pipe 14 to the outside.
The conventional heat exchanger distributes refrigerant to the upper and lower passages and thus remarkably reduces refrigerant pneumatic resistance within the respective header tanks.
However, the conventional heat exchanger does not effectively separate refrigerant into liquid and gas. In addition, because the separate member 7 and collecting chamber 12 functioning as a receiver tank are provided respectively to the header tanks 4, the heat exchanger has a relatively large size.
In the meantime, a Japanese Laid-Open Patent Publication Serial No. 7-103612 discloses a condenser which is integrally provided with a receiver tank at one end of header tanks in order to reduce the overall size.
As shown in FIG. 7, the condenser 3 having the integral receiver tank comprises a condensation section 8, a receiver section 9 and a sub-cooling section 10, in which the condensation section 8 is connected to the outlet side of a compressor 2.
The condensation section 8 introduces liquid-gas refrigerant into the receiver section 9, which separates refrigerant into gaseous and liquid refrigerant and feeds liquid refrigerant into the sub-cooling section 10.
The sub-cooling section 10 is arranged under and adjacent the condensation section 8, and sub-cools liquid refrigerant introduced from the receiver section 9.
The condenser 3 is provided with a second header 16 having an upstream side connected with a lower end of the condensation section 8 and a lower side connected with an upstream end of the sub-cooling section 10. The second header 16 is divided by first and second baffles 41 and 42 into an upstream communication chamber 46, a downstream communication chamber 47 and the receiver section 9.
As a result, two phase refrigerant of gas-liquid flown out via the condensation section 8 is introduced into the receiver section 9 via the upstream communication chamber 46.
The first baffle 41 vertically arranged within the second header 16 is provided with a refrigerant inlet port 44 communicating with an upper end of the receiver section 9 and a refrigerant outlet port 45 opened to a lower end of the receiver section 9 so that refrigerant can enter the entire receiver section 9.
In FIG. 7, some of reference numbers which do not designate the above-described components are not explained.
As set forth above, the conventional condenser installs the receiver section in one of the header tanks to reduce the overall size thereof, allows whole refrigerant to flow into the receiver section 9 to improve responsiveness in respect to rapid load fluctuation in a cooling cycle 1, and installs the sub-cooling section 10 to completely remove bubbly gaseous refrigerant.
The conventional condenser includes the receiver section to realize effective sub-cooling. However, there is a drawback that the sub-cooling rate cannot be further raised at a point where liquid refrigerant returns and initially sub-cools after gaseous refrigerant of high temperature and pressure is initially introduced and condensed into gas and liquid.
Furthermore, the conventional condenser further comprises a site glass 4 for confirming whether or not refrigerant finely condenses, and thus fabrication cost disadvantageously increases.
The present invention has been made to solve the foregoing problems and it is therefore an object of the present invention to provide a multistage gas and liquid phase separation condenser for condensing and separating initially introduced gaseous refrigerant of high pressure into gas and liquid, by which after separated into gas and liquid, liquid refrigerant can be improved with sub-cooling rate while flowing through a pre-sub-cooling section and additionally in other sections.
Also, the invention has a multistage gas and liquid phase separation condenser designed according to a conditional expression, which follows the relative dimension ratio of sections during condensation of refrigerant, in order to realize optimum condensation efficiency regardless of the total size of the condenser.
According to an aspect of the invention, there is provided a multistage gas and liquid phase separation condenser comprising: an super heat cooling/condensing section dm1 for cooling gaseous refrigerant of high temperature and pressure, which is introduced into the section dm1, to remove excessive heat therefrom and condense gaseous refrigerant; a first condensing section dm2 placed over the super heat cooling/condensing section dm1 for recondensing gaseous refrigerant; a second condensing section dm3 placed over the first condensing section dm2 for recondensing refrigerant to a liquid ratio higher than in the first condensing section dm2, whereby refrigerant is introduced into a receiver section 400 after flowing through the second condensing section dm3; a first sub-cooling section dm4 placed downstream of the super heat cooling/condensing section dm1 for sub-cooling refrigerant more than in the super heat cooling/condensing section dm1, whereby refrigerant is introduced into the receiver section 400 after flowing through the first sub-cooling section dm4 to join liquid refrigerant from the second condensing section dm3; and a second sub-cooling section dm5 placed downstream of the first sub-cooling section dm4 for sub-cooling liquid refrigerant joined from the second condensing section dm3 and the first sub-cooling section dm4 and for discharging sub-cooled liquid refrigerant therefrom, wherein the sections dm1, dm2, dm3, dm4 and dm5 are divided from one another.